A randomised, cross-over trial of upright sitting versus alternate side lying during nebulised delivery of medication to improve the pattern of aerosol deposition in participants with cystic fibrosis

INTERVENTION: Participants will inhale 4mL technetium‐99m DTPA radioaerosol in two positions in random order throughout the nebulisation period of 20 minutes for each of the positioning regimens on two separte days: 1. Upright sitting: or 2. Alternate Side Lying: (alternated between left and right at each minute) The two study days will have a minimum of 48 hours washout between them and not greater than 7 days (to ensure clinical stability). After each nebulisation a gamma camera will perform a 20 minute deposition scan incorporating a 2 minute transmission scan to outline the three‐dimensional margin of the lung fields. This data will be reconstructed to determine the distribution of the deposited radioaerosol in the lungs. A 15% improvement in uniformity of deposition is the proposed minimum difference that would make the alternate side lying strategy worthwhile in CF patient populations. CONDITION: Cystic Fibrosis PRIMARY OUTCOME: The 3‐dimensional map of the lung fields will be divided into unit volumes (voxels). The amount of radioactivity in each voxel will be calculated. The standard deviation of the radioactivity across all voxels within the margins of the lung fields will be used as an index of uniformity of the pattern of deposition for each participant. SECONDARY OUTCOME: Proportion of the loaded dose (dose loaded in nebuliser ‐ residual remining in nebuliser post 20 minutes of inhalation in MBq) delivered to the body (decay corrected gamma camera body image dose in MBq). The concentration of the dose in the apical regions compared to the concentration for the whole lung. The 3‐dimensional map of the lung fields will be divided into unit volumes (voxels). The amount of radioactivity in each voxel will be calculated. The ratio of apical:non‐apical deposition of radioactivity will be determined by the mean number of counts per voxel in the apical one third of the lung field divided by the mean number of counts per voxel in the basal two thirds of the lung field. The proportion of the delivered dose (dose loaded in nebuliser ‐ residual remining in nebuliser post 20 minutes of inhalation in MBq) that deposited in the lungs. (decay corrected lung gamma camera image dose in MBq). INCLUSION CRITERIA: INCLUSION CRITERIA: To participate in this study, a person must: 1 be 18 years of age or older 2 be able to read, write and comprehend English 3 have cystic fibrosis, diagnosed by sweat test or genotyping 4 have an FEV1 within 10% of the best recorded value as an outpatient during the previous 6 months 5 be willing to inhale a 4mL radioaerosol and undergo a 20min gamma scan, on two occasions.